Rotary drum dryer

ABSTRACT

Disclosed is a dryer for comminuted or powdered material, such as grain particles, having an outer drum and an interior element through which a heating medium such as steam is circulated, the drum and the interior element being concentric and rotated independently of each other. The drum rotates on a vertically tilted longitudinal axis so that material to be dried moves by gravity through the rotating drum which has vanes or lifts for raising the material to fall through the heated interior element. The assembly is characterized by use of seals through which air is drawn into the drum and air intake openings at both ends of the drum.

ied tats Sheehan atent 1 [4 1 Dec. 10, 1974 1 ROTARY DRUM DRYER [76]inventor: Daniel]; Sheehan, PO. Box 430,

Danville, 111. 61832 22 Filed: May 6, 1974 [21] App]. No.: 466,958

I [52] US. Cl 34/134, 34/138, 34/242, 165/88, 165/92 [51] Int. Cl. F26b11/02 [58] Field of Search 34/138, 134, 142, 135, 34/137, 128, 130, 242;165/88, 92

' [56] References Cited v UNITED STATES PATENTS I 548,651 10/1895 Lamb34/138 1,573,144 2/1926 Credo 34/17 1,928,004 9/1933 Bullerjahn....34/129 2,095,086 10/1937 Slemmer 34/135 Primary E.\'aminer-Kenneth W.Sprague Assistant Examiner-Larry l. Schwartz Attorney, Agent, orFirmWoodard, Weikart, Emhardt & Naughton [57] ABSTRACT Disclosed is adryer for comminuted or powdered material, such as grain particles,having an outer drum and an interior element through whicha heatingmedium such as steam is circulated, the drum and the interior elementbeing concentric and rotated indepen dently of each other. The drumrotates on a vertically tilted longitudinal axis so that material to bedried moves by gravity through the rotating drum which has.

vanes or lifts for raising the material to fall through the heatedinterior element. The assembly is characterized by use of seals throughwhich air is drawninto the drum and air intake openings at both ends ofthe drum.

3 Claims, 6 Drawing Figures SHE DEC

Fig.2

PATENIEI] 0E0 10 m4 SHEEI 30F 4 Fig. 4

ROTARY DRUM DRYER BACKGROUND OF THE INVENTION Dryers of the counterrotating type are not unknown in the prior and an example of prior artstructures is disclosed in Bullerjahn U.S. Pat. No. 1,928,004. Thestructure of the present invention distinguishes over the prior art inthat, among other things, it utilizes adjustableair intake registers atboth ends of the drum, one being adjacent to the subatmospheric airoutlet duct from the drum and acting as a partial by-pass for incomingair thus controlling the air intake from the register .at the oppositeend of the drum and the pressure drop across the seals. By permittingair to be drawn through the structural seals, leakage is always inwardand the area around the exterior of the dryer installation is kept freeof dust and particles passing through the dryer. The air moving inwardlythrough the seals may be sufficient to provide the desired air flowthrough the dryer, however, the presence of the intake registers permitsmore flexible control of this air flow component of the dryingoperation.-

I BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERREDEMBODIMENT Referring initially to FIG. 1, the assembly of the presentinvention includes a stainless steel drum having a clean out door 11.Thedrum I0 is essentially an open ended cylinder with one end closed bythe housing 12 and the other end closed by the stationary plate 13. Amaterial inlet tube 14 communicates with an aperture assembly showngenerally along the in the plate 13 and provides for entry of finallydivided or granulated material, such as grain to be dryed into the drum.The housing 12 at the opposite end of the drum is provided with amaterial discharge fitting 16 at its base and atits upper portion, anair discharge duct 17 extends tangentially'sidewardly, the duct 17 beingmore clearly visible in FIG. 5.

The drum is rotated about its longitudinal axis by means of a chain 18which extends around the drum and is driven by a drive member 19 rotatedby the electric motor 21. The drum is supported for rotation on trunnionrings 22 whichrest upon trunnion rollers 23 and thrust rollers 24 (FIG.4).- The rollers and the shaft extending through the drum are supportedby a support frame 20.

The longitudinal axis of the drum is tilted downwardly slightly, thatis, its left-hand end, as viewed in FIG. 1,.is slightly lower than itsright-hand end so that materialintroduced through the inlet 14 willmove, by

, gravity, through the length of 'the drum to be discharged through thedischarge fitting 16. Extending axially through the drum is a centralshaft 31 supported on bearings 32 and 33. As may best be seen in FIG. 3,a conventional rotary steam union fitting, indicated generally at 34 isattached to the shaft 31 and permits introduction of steam throughinterior passages in the shaft to a steam head, indicated generally at36 in FIG. 3, whose purpose will be subsequently more fully described.

Referring'now primarily to FIG. 3 and 3A, an inwardly extending endportion 37 on the drum is pro vided with a marginal offset flange andthe stationary plate 13 is provided with an adjacent, parallel, annularflange 13a and, as indicated by the air flow arrows in FIG. 3A, when thepressure within the drum is below atmospheric, air will move through therestricted space between the annular flanges 37a and 13a into the drum.

The housing 12, as may best be seen in FIG. 3, at its rightward marginforms the air discharge passage 17 and the material discharge passage16. Within thev ported on the shaft 31. The shaft and the heatingelement 36 rotate independently ofthe drum 10, the drive for therotation of shaft 31 being provided by the electric motor 41 (FIG. 1)which, through the drive member 42 chained to the sprocket 43, rotatesthe shaft and, hence, the heating element.

Referring primarily, again, to FIG. 3 it will be evident that theheating element includes a steam chest or header 46 through which steamfrom the fitting 34 circulates through tubes 47. The tubes 47 extendthrough a drain chamber 48 and through larger diameter tubes 49. Thetubes 49 extend into apertures in a tube support plate 51 and are cappedadjacent the plate. The

smaller diameter tubes 47 terminate short of the capped ends of thetubes 49 permitting steam to circulate back into the drain chest 48, asis conventional in the art. As will be evident from FIG. 4, the plate51, near its center, is provided with multiple, relatively large areaopenings 52 which permit entry of material moving through the inlet duct14 into the interior of the drum. Extending radially inwardly from theinterior of the drum are a series of spaced lifter blades 53 whichfunction to'raise the grain within the drum as the drum rotatesdepositing it onto the moving steam-heated tubes 49 of the heatingelement. Since the tubes of the heating element and the drum are rotatedat different speeds, as is conventional, the grain or other finallydivided material within the drum is repeatedly dropped 7 over the heatedtubes, the temperature of the grain I amount of air drawn through thevarious annular flange seals. As may best be seen in FIG. 2 thestationary plate 13 is also provided with grill covered openings 61 and62, whose effective area may be adjustable, which permits entry of airthrough the plate into the drum at its end remote from the material andair discharge openings 16 and 17.

In operation, with the tubes 49 heated by steam circulatingtherethrough, and with the heating element 36 and the exterior drum 10rotating at the desired speeds,

- finally divided material may be'introduced through the duct 14.Finally divided material will be turbulently lifted and dropped throughthe moving, heated tubes 49 and contact with the heated surface of thetubes will transfer heat, by conduction, to the finally dividedmaterial. The interior of the drum 10 is at sub-atmospheric pressurebrought about by operation of the exhaust fan 70, in discharge duct 72,driven by the fan motor 71 (FIG. 5). The discharge duct 72 communicateswith the discharge passage 17, and upon operation of the fan air will bedrawn through the annular restricted space between the flanges 37a and13a and a and 12b. This air drawn through the restricted space betweenthe flanges is heated and expanded by contact with the heating element36 and flows through the drum and out the discharge duct 17. in itspassage through the drum the air takes up the moisture evaporated fromthe material moving through the drum and exits with its acquiredmoisture through the discharge duct 17. The material, releived of itsmoisture after passage along thelength of the drum, exits through thedischarge duct 16. Material may .be added'and withdrawn from the drum ona continuous basis.

The provision for-the intake of air into the drum through the flangeseals functions to retain the material being dryed inside the drum andinhibits any fine dust in the material in the drum from flushing out tothe exterior of the dryer. The rotating and sifting action provided bythe lifter blades 53 serves to blend the material passing through thedrum. The drum and the interior heating element may be rotated in thesame direction at differing speeds or in opposite directions dependingupon requirements. As previously mentioned, the adjacent flanges willnormally provide sufficient air induction area for normal operatingconditions, however, where necessary, the inlet registers or grills 12c,61 and 62 may be opened to increase the air inlet area.

I claim:

1. A rotary drum type dryer for grannular material comprising: arotatably mounted drum and an interior heating element mounted forindependent concentric rotation within the drum, means for independentlyrotating said drum and said heating element, a stationary plate at oneend of said drum having a material inlet tube extending therethrough andinto the drum interior, annular adjacent flanges on said drum and saidplate defining an annular restricted air intake passage from theexterior to the interior of the drum, a stationary housing at the otherend of said drum into which said drum extends, adjacent annular flangeson said drum and said stationary housing defining a further annularrestricted air intake passage to the interior of said drum and housing,a material discharge opening at the base of said housing and an airdischarge opening at the upper end of the housing,'and air moving meansfor drawing air from said' drum through said air discharge opening.

2. A rotary drum type dryer as claimed in claim 1 in which auxiliary airinlet passages are provided in said housing adjacent said air dischargeopening and in said stationary plate for admitting air into said drumand housing other'than through the space between said adjacent annularflanges.

3. A rotary drum type dryer as claimed in claim 2 in which the effectivesize of said auxiliary air, inlet passages in said housing areadjustable.

1. A rotary drum type dryer for grannular material comprising: arotatably mounted drum and an interior heating element mounted forindependent concentric rotation within the drum, means for independentlyrotating said drum and said heating element, a stationary plate at oneend of said drum having a material inlet tube extending therethrough andinto the drum interior, annular adjacent flanges on said drum and saidplate defining an annular restricted air intake passage from theexterior to the interior of the drum, a stationary housing at the otherend of said drum into which said drum extends, adjacent annular flangeson said drum and said stationary housing defining a further annularrestricted air intake passage to the interior of said drum and housing,a material discharge opening at the base of said housing and an airdischarge opening at the upper end of the housing, and air moving meansfor drawing air from said drum through said air discharge opening.
 2. Arotary drum type dryer as claimed in claim 1 in which auxiliary airinlet passages are provided in said housing adjacent said air dischargeopening and in said stationary plate for admitting air into said drumand housing other than through the spaCe between said adjacent annularflanges.
 3. A rotary drum type dryer as claimed in claim 2 in which theeffective size of said auxiliary air inlet passages in said housing areadjustable.